Rwanda's President Paul Kagame has been re-elected with 99.18% of the vote, the National Electoral Commission said on Thursday, extending his near quarter-century in office.

The two men standing against him - Frank Habineza from the Democratic Green Party and independent Philippe Mpayimana - both conceded defeat in Monday's election, which rights groups say was marred by a crack-down on journalists, the opposition and civil society groups. A government spokesperson repeatedly rejected such criticism during the election period.

Oda Gasinzigwa, chairperson of the National Electoral Commission, told a news conference that voter turnout was 98.20% of the nine-million registered voters.

The final election results are due to be announced no later than July 27, she said.

Kagame, who got more than 93% of the vote in the last three elections, has won praise from Western and regional leaders for helping to end the 1994 genocide in Rwanda and rebuilding the country into an attractive destination for investment and aid.

His reputation has been damaged, however, by accusations of abuses at home and supporting rebels in neighbouring Democratic Republic of Congo - allegations he has repeatedly denied.

The electoral commission barred eight other candidates, including Kagame's most vocal critics, from running, citing a range of reasons including missing and incomplete registration documents.